msd-core/docs/TESTING-SUITES.md

Testing Suites

This project's tests/ directory uses filename suffix markers to group tests into named suites. The harness scripts/run-tests.cjs filters by suite when given --suite <name>. Without a flag it runs every *.test.cjs file (the historical default — unchanged).

Tracked by issue #3597.

Suites

Suite	Filename pattern	What goes here
unit	*.test.cjs (no other marker)	Default fast lane. Pure logic, no network, no external processes beyond gsd-tools. Most tests live here.
integration	*.integration.test.cjs	Cross-module flows: full installer end-to-end, multi-tool orchestration, anything that crosses two or more bin entry points.
install	*.install.test.cjs	Tests that perform a real install/uninstall against a sandbox project. Slower; PR CI skips these on PRs and runs them on main push only.
security	*.security.test.cjs	Adversarial input, prompt-injection guards, fixture-driven hostile-payload sweeps.
slow	*.slow.test.cjs	Anything that routinely takes >5s wall-clock or holds significant memory.
qa	*.qa.test.cjs	End-to-end walks that drive the real gsd-tools binary across multiple loop steps against one accumulating temp project, with invariant oracles after every step. Slower than unit; excluded from the fast lane.
all	(any)	Explicit alias for "no filter". Equivalent to running with no --suite flag.

How to place a new test

1. Pick the most specific bucket above.
2. Name the file with the matching suffix: tests/<feature>.<suite>.test.cjs.
3. If unsure, leave the suffix off — the file lands in unit, the default fast lane.

Examples:

• tests/agent-frontmatter.test.cjs — unit
• tests/prompt-injection-guards.security.test.cjs — security
• tests/installer-end-to-end.install.test.cjs — install
• tests/sdk-mutation-stress.slow.test.cjs — slow
• tests/loop-walk.qa.test.cjs — qa

The suite-suffix convention was chosen over a directory layout (tests/security/) so the 545+ existing test files don't need to move. Existing files all classify as unit until someone explicitly retags them.

Regression tests

Do not create new top-level tests/bug-NNNN-*.test.cjs, tests/fix-NNNN-*.test.cjs, or tests/issue-NNNN-*.test.cjs files. Add the regression case to the owning module's main test file instead (e.g. a describe('regressions') block in tests/<module>.test.cjs).

node --test spawns one child process per FILE, so file count — not test count — is the unit of CI overhead, and it is worst on Windows lanes where every spawn is Defender-scanned. The 2026-06 CI audit found 244 one-off bug-* files (~38% of the suite). That population is grandfathered in scripts/lint-regression-test-names.allowlist.json and enforced by an identity ratchet (npm run lint:regression-names, part of npm run lint:ci), which also bans fix-* and issue-* NNNN-prefixed files the same way:

• A new bug-*, fix-*, or issue-* NNNN-prefixed file fails CI — fold it into the owning module's file.
• Deleting/consolidating a grandfathered file requires pruning its allowlist entry, so the baseline only ever shrinks.
• Inherited drift (the failure names files your PR didn't add — e.g. the base branch merged bug-*/fix-*/issue-* files without feeding the allowlist, or you rebased and carried a pre-rebase allowlist): run node scripts/lint-regression-test-names.cjs --update and commit the regenerated allowlist. Snapshot artifacts like this allowlist (and docs/INVENTORY.md) must be regenerated after rebasing, never carried through a rebase.

A folded suite may appear only once per host

When a standalone file is folded into its owning module's test file, the moved suite is wrapped in a self-contained block carrying a marker:

// ────────────────────────────────────────────────────────────────────────
// Folded from tests/bug-376-claude-js-hook-gsd-rewriter.test.cjs — …
// ────────────────────────────────────────────────────────────────────────
{
  const { describe: __foldDescribe } = require('node:test');
  __foldDescribe("folded:bug-376-claude-js-hook-gsd-rewriter (…)", () => { … });
}

Because the block is self-contained, a second verbatim copy in the same host parses, registers, and passes — twice. Nothing in a green suite reports it. #3271 found 25 such copies (~5,800 lines) across three install suites, all from a single stale-base re-application during the consolidation epic. The cost is not only wasted CI on every lane: it is a DEFECT.GENERATIVE-FIX trap, because a contributor fixing one of those regressions edits the copy they found and leaves the other asserting the old behavior, with the suite still green.

local/no-duplicate-fold-marker (eslint-rules/no-duplicate-fold-marker.cjs, error under tests/**/*.cjs) reports the second and every later occurrence of a folded:<marker> title in one file, naming the line the first occurrence sits on. When it fires, delete the copy it points at — the two blocks are the same suite, so the fix is removal, never an eslint-disable.

It keys on the whitespace-delimited token after folded:, which matters in both directions. A narrower key that stops at . would collide feat-443-effort-fast-mode.integration with feat-443-effort-fast-mode — two genuinely distinct suites that coexist in tests/model-resolver.test.cjs. Keying on the whole title instead would let a re-fold under a different batch label slip through, which is exactly the shape #3271 took. Titles without a folded: prefix, non-literal titles, and the same marker appearing in two different host files are all left alone.

The ratchet deliberately covers only bug-*. Files named feat-NNNN-* / enh-NNNN-* are feature test files — one (or one per suite) per feature is the sanctioned layout (see the #443 strategy below), not a one-off regression pattern. If issue-*/perf-* one-offs start accumulating the same way bug-* did, extend the ratchet's regex and regenerate the allowlist.

Workflow & agent size budget

Tracked by issue #1074. Bytes (not lines) per #717; LF-normalized per #683.

Workflow files (gsd-core/workflows/*.md) and agent files (agents/gsd-*.md) both ship in the installed runtime and are loaded into context — workflows on every command, agents on every subagent dispatch — so their byte size is a real cost. Two sibling guards (tests/workflow-size-budget.test.cjs and tests/agent-size-budget.test.cjs) keep that cost from creeping up invisibly, sharing one byte-counter (measureMdFiles). Growth is caught by two independent layers:

Layer	What it does	Where
Differential attribution size ratchet (primary, #2724 / ADR-2719 §4)	The same computed-attribution check that replaced the golden-install-parity fixtures also reports growth in any gsd-core/workflows/*.md or agents/gsd-*.md file, with the exact byte delta, comparing PR HEAD against next. Unacknowledged growth is a hard failure; shrinkage needs no acknowledgment. No committed snapshot — nothing to regenerate by hand.	tests/emitted-attribution.test.cjs (real-tree test) via tests/helpers/emitted-diff.cjs
Loose tier hard caps (backstop)	Absolute outer red lines per tier — workflows: XL ≤ 98304, LARGE ≤ 61440, DEFAULT ≤ 40960 bytes; agents: XL ≤ 57344, LARGE ≤ 49152, DEFAULT ≤ 24576 bytes. A cap is never raised when a file approaches it: crossing it means extract, not bump. Independent of the ratchet above — unaffected by #2724.	XL/LARGE/DEFAULT_CAP in each guard file

discuss-phase.md additionally has a thin-dispatcher target of < 32000 bytes (the discuss-phase progressive-disclosure split, #717). A net-new agent is DEFAULT-tier and already bounded by the DEFAULT cap — no separate new-agent cap is needed. (This tier-cap machinery is distinct from the separate 45 KB-char extraction-evidence threshold on gsd-planner enforced by tests/planner-decomposition.test.cjs — that one proves mode sections were extracted; this one bounds total agent bytes.)

How-to: a workflow or agent grew and CI is red

The differential attribution check reports the file and the byte delta. To resolve:

1. Justify the growth in your PR (a sentence in the description is enough) — the acknowledgment entry (below) is the review record that the larger size was a deliberate, seen decision, not silent drift.
2. Add an acknowledgment fragment under tests/emitted-drift-acks/ naming the file and the reason, per CONTRIBUTING.md's "Editing shipped content" section and CONTEXT.md's ### Emitted Artifact Provenance entry. Name the fragment for your issue or PR (something nobody else is using) — the failure output prints a minimal valid document you can paste. This is deliberately a per-PR fragment, not one shared file: two fragments can never merge-conflict with each other, and a fragment appearing in your diff is the visible signal. They do, however, share a path key space. If the failure instead names a path a merged PR already acknowledged (a spent entry sitting in an existing fragment), you have two routes and the error text names both: git rm that fragment if every entry in it is spent — it gates nothing and only holds the keys — or, if it is still live, reword/extend its reason in place to explain the new ripple. Either way, do not add a duplicate entry for the same path; two ack sources naming the same path is a hard, loudly-reported error. The legacy single tests/emitted-drift-ack.json is still read and unioned in for branches that carry it, but new acknowledgments never go there.
3. Delete your fragment once it has merged (#3078). A fragment on next is spent by definition — its prose is already at the base, so it can no longer clear anything — while still owning its path keys, which walls off the next PR that grows one of them. The guard-no-ack-on-next job reds next and prints the exact git rm for every fully-spent fragment. A partially spent fragment is deliberately left alone.
4. Or shrink it instead of acknowledging. Prefer extraction when the growth is incidental: for a workflow, move per-mode bodies to workflows/<name>/modes/, templates to workflows/<name>/templates/, and shared prose to gsd-core/references/; for an agent, lift shared boilerplate into gsd-core/references/ and @-reference it — then load it LAZILY. Do not convert them to eager @-required_reading includes: that shrinks the file's bytes without shrinking loaded context, so it games the guard while making the real cost worse. See workflows/discuss-phase/ for the progressive-disclosure pattern.

If a hard cap (not the ratchet) is what failed, an acknowledgment will not help — that is the signal to extract, per step 3.

Reference

Artifact	Role
scripts/workflow-size.cjs	Single source of truth — LF-normalized byte counter (lfByteCount) + generic measureMdFiles(dir, predicate) (backs both workflows and agents) + workflow enumeration (listWorkflowStems, measureWorkflows). Imported by both guards and by tests/helpers/emitted-runtime.cjs's currentSizes() so they can never measure differently.
tests/emitted-attribution.test.cjs + tests/helpers/emitted-diff.cjs	The differential attribution check and its size ratchet (ADR-2719). The sole mechanism for both emitted-content propagation AND per-file size growth as of #2724.
tests/emitted-drift-acks/	Per-PR acknowledgment fragments (primary, #2914) for unattributable emitted-content ripples and for size growth. A fragment appearing in your diff is the alarm; absence is the healthy steady state.
tests/emitted-drift-ack.json	Legacy single acknowledgment file, superseded by the per-PR fragments above. Still read and unioned in for branches that carry it; must never gain new entries and must never persist on next (enforced by guard-no-ack-on-next via scripts/lint-emitted-drift-ack.cjs --guard-next).
npm run regen:derived	Runs every remaining generator in dependency order (build → registry → ADR index → capability matrix → inventory manifest → manifest versions → tests/fixtures/install-tree/*.json).
tests/workflow-size-budget.test.cjs	The workflow tier hard-cap guards, plus the discuss-phase progressive-disclosure checks.
tests/agent-size-budget.test.cjs	The agent tier hard-cap guards (the agent analog).

tests/workflow-size-baseline.json, tests/agent-size-baseline.json, tests/fixtures/golden-install-parity/*.json, scripts/update-size-baseline.cjs (npm run size:baseline), and scripts/git-merge-regen-driver.cjs (npm run setup:merge-driver) are all removed by #2724: they were pure functions of the source tree, conflicted on every merge that touched them, and their functions are now served by the differential attribution check above. tests/fixtures/install-tree/*.json is the one artifact family that stays committed and normally-merged (ADR-2719 §7) — it conflicts on 0 of 7, its diffs are readable, and it preserves "the installer stopped shipping X" as a hard absolute failure with no attribution reasoning involved. Regenerate it with npm run gen:install-tree (folded into npm run regen:derived).

The QA smell ratchet

tests/loop-walk.qa.test.cjs (the qa suite) is the QA-walk harness's own self-test. Separately, scripts/qa-smell-ratchet.cjs drives that same harness end to end against the real gsd-tools binary and turns its findings into a CI gate — run it with npm run lint:qa-smells.

The gate has three independent inputs. The harness's oracles (tests/qa/oracles.cjs) supply the first two:

• A violation is the engine breaking a documented contract. It always fails the build — baseline or no baseline, acknowledged or not.
• A smell is legal-but-questionable behavior. A smell never fails a build on its own merits. What fails is the absence of a decision about it: an unacknowledged NEW smell, or a STALE entry in tests/qa/smell-baseline.json (one that stopped firing — the baseline is shrink-only, so a fixed or changed scenario must be pruned, not left behind).

The third comes from the scenarios themselves, not from an oracle:

• A scenario expectation failure is a step's declared expect not holding — the scenario asserted percent: 100 and the engine returned something else. Like a violation, it is never acknowledgeable: it carries no fingerprint, so there is no key to put in a baseline entry or an ack fragment. Fix the engine, or correct the expectation.

Expectation failures were invisible to the gate until #3597: buildReport counted them in totals.violations while collectFindings read only oracle violations, so a failing scenario printed 0 violations and exited 0. The multi-workstream scenario failed on every CI run for three weeks without reddening a build. The invariant that keeps the two honest — asserted in tests/loop-walk.qa.test.cjs — is:

collectFindings().violations.length
  + collectFindings().expectationFailures.length
  === report.totals.violations

Note also that scripts/qa-smell-ratchet.cjs only invokes its own main() under require.main === module. That guard is what lets the QA suite require() the script to test collectFindings without kicking off a real 20-scenario walk as an import side effect — the reason the gate's own logic had no test before #3597.

Every smell must terminate in exactly one of TWO states — there is no third "accepted with a good explanation" state:

1. REAL — an assigned defect. File it, then acknowledge the smell with an entry (baseline entry or tests/qa/smell-acks/ fragment) carrying that issue number.
2. FALSE POSITIVE — the oracle itself is wrong. Fix the oracle (tests/qa/oracles.cjs) so it stops firing. It is NEVER baselined.

When the ratchet reports a NEW smell, there are exactly two legitimate responses — fix the detector, or file a defect and cite its issue number:

1. Fix the underlying behavior (or the oracle, if it's a false positive) so the smell stops firing.
2. File a defect and acknowledge it by adding a fragment under tests/qa/smell-acks/ — the ratchet's failure output prints a paste-ready skeleton naming the required key, id, scenario, and issue fields. issue MUST be a positive integer naming the tracking issue; a free-text reason may accompany it as an optional human note but can NEVER substitute for issue — "write an explanation" is not a way to acknowledge a smell. See tests/qa/smell-acks/README.md for the full shape and lifecycle.

Run node scripts/qa-smell-ratchet.cjs --update to regenerate tests/qa/smell-baseline.json from the current run, folding in any acked fragments and pruning stale entries. --update never invents an issue number: a genuinely new smell is written with issue: null and a TODO reason, and the very next plain (non---update) run REJECTS that entry — forcing a human to triage it before it can ship. The baseline only ever shrinks: growth happens by adding an acknowledgment carrying a real issue number (a reviewable diff), never by widening the generator's tolerance and never by prose alone.

Running suites locally

npm test                    # everything (backcompat — same as before)
npm run test:unit           # only unit
npm run test:integration    # only integration
npm run test:install        # only install
npm run test:security       # only security
npm run test:slow           # only slow

npm run test:coverage       # backcompat — coverage over EVERY test
npm run test:coverage:unit  # fast coverage signal — only unit suite
npm run test:coverage:all   # alias for test:coverage

Direct harness invocation also works:

node scripts/run-tests.cjs --suite security
node scripts/run-tests.cjs --suite=security
node scripts/run-tests.cjs --files "tests/command-contract.test.cjs tests/core.test.cjs"
node scripts/run-tests.cjs --files-from .ci-selected-tests.txt

npm run test:affected (scripts/run-affected-tests.cjs) is a local-only convenience that selects tests via the require() dependency graph of your working-tree diff. CI does not use it — CI selection is the rule table in scripts/ci-test-scope.cjs, which is the authoritative mapping. If the two disagree, trust (and fix) the rule table.

Unknown suites exit non-zero with the list of valid suites. Empty suites (e.g. --suite security before any security-tagged file exists) exit 0 with a no tests in suite "..." notice on stderr so CI lanes don't go red while a suite is being populated.

The live-config hermeticity guard

Every run-tests.cjs invocation snapshots GSD's own install footprint in each live runtime config directory before the suite and re-checks it afterwards. It exists because the failure it catches is silent by construction: a test that resolves a config directory from the ambient environment instead of a sandbox writes into your real ~/.claude (or $GSD_HOME/.gsd, or a Kimi config.toml), and nothing reports it. CI cannot catch this class at all — CI never has CLAUDE_CONFIG_DIR and friends set.

The guard watches only what GSD unambiguously owns — its top-level install footprint plus gsd--prefixed children of directories shared with the host agent — never whole config roots, because a host agent legitimately writing history.jsonl mid-run would make the guard cry wolf, and a guard that cries wolf gets switched off.

Two environment variables control it:

Variable	Effect
GSD_STRICT_LIVE_CONFIG_GUARD=1	A detected write fails the run. Set on the Linux/macOS lanes of every CI job that runs the suite.
GSD_SKIP_LIVE_CONFIG_GUARD=1	Skips the check entirely.

Unset, the guard reports and does not fail — deliberately, not timidly. On its first CI run it surfaced pre-existing leaks on the Windows lane, where os.homedir() reads USERPROFILE and ~190 test sites sandbox HOME alone. Those are real and worth fixing, but they are a different defect class, and a brand-new gate that instantly reds an unrelated lane gets reverted rather than obeyed. Windows lanes therefore stay report-only until that sweep lands; this repo has the pattern already, in the local/no-source-grep ESLint rule that shipped at warn and was promoted to error after its cleanup (ADR 452).

GSD_SKIP_LIVE_CONFIG_GUARD is a bypass on a safety check, so it is documented here rather than left to be discovered in the source: an undocumented bypass is one people eventually set without knowing what they turned off. If you need it routinely, that is a bug report, not a workflow.

Reported paths are labelled CREATED, MODIFIED, DELETED, or UNVERIFIED. UNVERIFIED means a scan bound was hit and the path could not be attested either way — it is never the same as clean.

The mergeability preflight

Before any of the matrix below is provisioned, every pull_request compute lane waits on one shared gate: PR mergeability, the reusable workflow .github/workflows/pr-mergeable-preflight.yml. A pull request with a merge conflict runs no CI at all until the conflict is resolved (#3833).

Reference

Verdict	When	Job result	Effect on the pipeline
MERGEABLE	GitHub reported mergeable: true	success	everything runs as normal
CONFLICTED	GitHub reported mergeable: false	failure	every gated job is skipped; Required tests and Stryker mutation score report red
INDETERMINATE	mergeability still unknown after the retry budget, or the API read failed	success (fails open)	everything runs as normal; a ::warning:: is emitted
SKIPPED_NOT_A_PR	the event is not pull_request (push, workflow_dispatch, a release.yml call into install-smoke.yml)	success	everything runs as normal; zero API calls
INDETERMINATE (bootstrap)	scripts/ci-pr-mergeability.cjs is absent at the base sha	success (fails open)	everything runs as normal; a ::warning:: names the cause

The bootstrap row is a consequence of the checkout being pinned to the base sha: the preflight runs the script as it exists on the base branch, so the script is absent on the pull request that introduces it, and on any branch whose base predates it. Absent is not "conflicted" — it is one more thing the gate cannot determine, so it takes the same fail-open path. The arm is self-healing and never fires again once the script is on the base branch; a test pins it in place so a future reader does not mistake it for dead code.

The verdict comes from scripts/ci-pr-mergeability.cjs, which polls GET /repos/{owner}/{repo}/pulls/{number} until mergeable is non-null. GitHub computes mergeability in an asynchronous background job and returns null while it is in progress, so a single cold read is never authoritative — the poll is required, not defensive.

Two properties are load-bearing and easy to break:

• Only mergeable === true / === false decides the verdict. null is falsy, so a truthiness test (if (!mergeable)) would classify every cold read as a conflict and red every PR in the repo.
• mergeable_state never decides the verdict. Its blocked value means "required checks have not passed", which is true while this very job is running — gating on it self-deadlocks the pipeline. It is read for the failure message only.

Gated: test.yml (lint-tests, test, test-inert, test-full, coverage-gate, qa-loop-walk, required-tests), install-smoke.yml, mutation.yml, security-scan.yml, docs-required.yml, changeset-required.yml, default-flip-documentation.yml, branch-naming.yml.

Deliberately not gated: the pull_request_target policy and security lanes — auto-close-unsolicited-PRs, close-draft-PRs, the target/title/template validators, issue-link, and unauthorized-approval dismissal. Gating those would let a conflicted drive-by PR evade auto-close, so they keep running on a conflicted PR and a test asserts they are never wired to the preflight.

What it deliberately does not do

It applies no label. The gate does not add or remove needs-review: merge-conflict. Eight caller workflows each invoke the preflight, so eight jobs would race to add-or-remove one label on every PR event, and it would force pull-requests: write into eight lanes that today hold contents: read. needs-review: merge-conflict stays a maintainer triage label applied during PR sweeps; the red check and its annotation are the machine signal.

It changes no branch protection. .github/rulesets/main-protection.json is untouched and needs no new required context — GitHub natively refuses to merge a pull request with conflicts, so the ruleset already blocks it. (Adding the check as required before the workflow exists on the base branch would deadlock every open PR until it landed.)

What this does not replace

scripts/ci-rebase-check.cjs is unchanged and still runs inside each matrix job, including its #2472 base-sha pin. The preflight is an early-exit optimization on GitHub's asynchronously-computed view; the in-job merge remains authoritative and covers the case where the base advances mid-run. The gate is never a safety property — every path except an explicit mergeable: false fails open, so an API outage simply restores the pre-#3833 behavior.

If your PR shows a red PR mergeability check

The annotation names the base branch and the remedy. There is one step:

git fetch origin && git rebase origin/next && git push --force-with-lease

Resolve the conflicts the rebase reports, then push. The next synchronize event re-runs the preflight and the full pipeline comes back. (Because the sequence is a single command, this has no separate how-to page — see CONTRIBUTING.md → Where Do I Open My PR? for the branching model that makes the rebase necessary in the first place.)

Note the interaction with the sha-bound pass marker: a rebase changes your HEAD sha, which invalidates any prior remote-runner verification. Rebase last.

CI matrix

The Tests workflow runs every PR through a scoped gate generated by scripts/ci-test-scope.cjs.

All lanes run on Node 24 — the engines.node floor (>=24.0.0) and the only supported runtime.

Lane	Scope
ubuntu-latest (scoped)	scoped tests — fast PR signal
ubuntu-latest (full, sharded)	unit + integration + security
windows-latest	scoped Windows/path/shell tests
macos-latest	full parity when required

• Scoped tests are selected from the changed paths, plus a small CLI/package smoke set. They are for confidence on the affected surface, not for counting tests.

The default PR gate runs the broad unit (under the c8 coverage gate), integration, and security suites once on Ubuntu / Node 24, scoped tests on a second Ubuntu / Node 24 lane, and scoped tests on Windows / Node 24. "Scoped" means the diff-selected list from the rule table — not the full suite and not a fixed smoke set (the fixed smoke list is only the empty-selection fallback). The Windows lane's list is the Windows-sensitive subset of the selection, plus every changed test file, unconditionally (the #494 invariant, narrowed): a modified test is exercised on the divergent OS before merge at per-file cost, without paying for the three full parity lanes.

PRs touching workflow, package, test-runner, install, release, or Windows-sensitive surfaces also run the full parity matrix on macOS and the older Windows runtime, plus install and slow on the primary Ubuntu lane. Everything (including the full parity matrix) runs on every push to next, which covers the residual macOS / Windows cross-product for scoped PRs.

Coverage runs inside the Ubuntu / Node 24 full lane (not a separate job — that duplicated the entire unit run) and stays single-lane because multiplying coverage across OS/runtime lanes adds cost without improving the threshold signal. Note the gate's deliberate blind spot: it measures gsd-core/bin/lib/*.cjs only — scripts/, hooks/, and bin/ are unenforced, and stryker.config.mjs additionally excludes ~48% of lib lines from mutation testing (see the UNMUTATED list there). Widening either gate is tracked work, not an accident to "fix" silently by raising thresholds.

To inspect the scope locally:

npm run ci:test-scope -- --files "commands/gsd/plan-phase.md"
node scripts/ci-test-scope.cjs --base origin/next --head HEAD

Chunk packing and the test timing table

scripts/run-tests.cjs does not hand the whole selected file list to one node --test process. It packs the files into chunks, each spawned separately, because Windows caps a command line at 32,767 characters and because each chunk gets its own 600s timeout (RUN_TESTS_CHUNK_TIMEOUT_MS) and a fresh process, which bounds memory pressure.

How files are distributed across those chunks decides whether the slowest chunk sits near that timeout while the others idle. The packer weights each file by its measured duration, read from tests/test-timings.json, and places files with LPT (longest-processing-time-first: heaviest file first, each into the currently lightest chunk). Before #2456 the weight was guessed from the filename, which mis-ranked files badly enough that the slowest chunk ran ~3.9x the lightest.

Reference

Knob	Default	Meaning
RUN_TESTS_MAX_FILES_PER_CHUNK	60	Per-chunk weight budget. Weights are normalized so an average-cost file weighs 1, so this still reads as "about 60 average files".
RUN_TESTS_MAX_CMDLINE_CHARS	28000	argv ceiling per chunk, with headroom under the Windows 32,767 limit.
RUN_TESTS_TIMINGS_FILE	tests/test-timings.json	Path to the timing table. Tests override it to inject a synthetic cost profile.
RUN_TESTS_CHUNK_TIMEOUT_MS	600000	Per-chunk timeout.

The timing table is advisory and deliberately un-gated. There is no --check mode and no CI lint that fails on staleness, because timing data legitimately varies run to run. A file missing from the table falls back to the table's median weight, and a missing or unparseable table falls back to uniform weight — so drift costs chunk balance, never a red build. A count-based floor additionally guarantees the packer never produces fewer chunks than plain count-based packing would, so a badly stale table cannot collapse the suite into a few fat chunks.

How-to: regenerate the timing table

Regenerate when the suite's cost profile has visibly drifted — after adding or removing expensive tests, not on a schedule. The input is a node:test reporter event stream from a gsd-test run:

node scripts/gen-test-timings.cjs \
  ~/.local/state/gsd-test/runs/<run-id>/test-events-linux-node24.jsonl \
  ~/.local/state/gsd-test/runs/<run-id>/test-events-macos-node24.jsonl

Pass every lane you have. A file's recorded time is the max across the supplied streams, not the mean: the packer exists to keep the slowest lane's slowest chunk away from the timeout, so the conservative bound is the right one. Keys are sorted so a regeneration diff shows only the files whose cost moved.

Best practices for forward-compat (Node 24/26)

• Use process.execPath when spawning Node in tests so each matrix lane exercises the lane's Node version.
• Avoid stack-trace or error-message prose assertions. Assert err.code, structured JSON fields, or enums — Node minor releases routinely tweak error wording.
• Prefer node:test, node:assert/strict, and node:test mocks. No external test frameworks.
• Coverage uses c8 and propagates NODE_V8_COVERAGE through the harness's child process.

---

Test strategy: #443 effort + fast_mode engine

Feature: unified cross-provider effort and fast_mode knobs (issue #443). Test files: tests/model-resolver.test.cjs (unit), tests/model-resolver.test.cjs (integration).

Testing pyramid

Layer	File	What it covers
Unit	feat-443-effort-fast-mode.test.cjs	Pure logic: cascade rules, clamping, escalation math, malformed config handling, schema key validation. No CLI subprocess.
Integration	feat-443-effort-fast-mode.integration.test.cjs	Architecture-level invariants: cross-provider validity, totality across the 33-agent registry, CLI JSON contract, config round-trip, fast-mode honesty. Real subprocesses via runGsdTools.
E2E (pending)	(not yet wired)	Propagation layer: effort frontmatter / CLAUDE_CODE_EFFORT_LEVEL env actually reaching a spawned Claude Code subagent. See "Gaps" below.

Architectural invariants

Each invariant exists to prevent a specific class of production failure.

(a) Cross-provider validity

What: renderEffortForRuntime(runtime, universalEffort).value must always be a member of the runtime's real provider enum. Ground-truth enums are defined as local constants in the test — not sourced from the implementation.

PROVIDER_EFFORT_ENUMS = {
  claude: Set { 'low', 'medium', 'high', 'xhigh', 'max' }   // Anthropic output_config.effort
  codex:  Set { 'minimal', 'low', 'medium', 'high', 'xhigh' } // OpenAI model_reasoning_effort
}

Why: Passing a value outside these sets results in a 400 from the real API. The clamping logic (max -> xhigh for codex; minimal -> low for claude) must hold for every cell of the VALID_EFFORTS × runtimes matrix.

(b) Param/channel contract

What: Each runtime exposes a stable param string (the native API field name) and channel (how the value is propagated). Unknown runtimes return param: null, channel: null and pass the effort value through unchanged.

Why: Callers read .param to construct the dispatch payload. A regression here would silently drop effort from subagent invocations.

(c) Resolve-execution JSON contract

What: The gsd-tools resolve-execution <agent> command emits a JSON object with all eight keys present and typed correctly: model (string), profile (string), effort (VALID_EFFORTS member), effort_rendered (string), effort_param (string|null), effort_propagation (string|null), fast_mode (boolean), fast_mode_supported (boolean).

Why: Orchestrators and workflow dispatchers parse this JSON. A missing or mistyped field silently breaks downstream consumers.

(d) Totality across the real registry

What: For every agent in the 33-agent registry, resolveEffortInternal returns a VALID_EFFORTS member (never undefined/null), resolveFastModeInternal returns a strict boolean, and renderEffortForRuntime('claude', effort) stays within the claude provider enum.

Why: A catalog addition that introduces a missing routingTier mapping would otherwise produce undefined and propagate silently.

(e) Fast-mode honesty invariant

What: When the runtime is claude, fast_mode_supported in resolve-execution output is always false, regardless of the fast_mode config. RUNTIMES_WITH_FAST_MODE contains only 'api'.

Why: Claude Code's /fast toggle is session-level only. Emitting fast_mode: true as frontmatter on a Claude subagent is a silent no-op. Advertising fast_mode_supported: true for claude would cause orchestrators to believe the knob was wired when it is not.

(f) Precedence first-valid-wins

What: Both effort and fast_mode use a layered cascade. The test table covers all four effort layers (invocation override → agent_overrides → routing_tier_defaults → default) and all five fast_mode layers, including the case where an invalid value at a higher layer correctly falls through.

Why: Silent precedence bugs (e.g., a numeric value in agent_overrides not being rejected) would override intentional user config.

(g) Dynamic-routing composition

What: resolveEffortForTier escalates effort by attempt number independently of the model tier mapping. The test verifies the effort ladder (low -> medium -> high -> xhigh -> max), the max clamp, the max_escalations cap, and that escalate_on_failure: false suppresses escalation entirely.

Why: Effort escalation and model escalation share configuration (dynamic_routing) but must operate independently; coupling them would cause over-escalation or under-escalation.

(h) Config-tooling round-trip

What: gsd-tools config-set accepts all new key namespaces (effort.default, effort.routing_tier_defaults.<tier>, effort.agent_overrides.<agent>, fast_mode.enabled, fast_mode.routing_tier_defaults.<tier>, fast_mode.agent_overrides.<agent>) without an "Unknown config key" error, and values set via config-set are reflected in resolve-execution output.

Why: The schema validation gate (VALID_CONFIG_KEYS + DYNAMIC_KEY_PATTERNS) is separate from the resolver logic. A key missing from the schema would produce a silent write failure and appear as a bug only at runtime.

Coverage targets

Suite	Target
Unit	Every cascade rule, every fallthrough, every clamp. All function branches in resolveEffortInternal, resolveFastModeInternal, resolveEffortForTier, renderEffortForRuntime.
Integration	All 8 architectural invariants. All 33 registered agents. All 6 provider × effort combinations for the valid-enum check. Full config-set key namespace.

Gaps / not yet covered

E2E orchestrator-spawn-propagation layer (pending follow-up wiring): The integration tests verify that GSD resolves and renders effort values correctly. They do NOT verify that the rendered values actually reach a spawned Claude Code or Codex subagent at runtime. Specifically uncovered:

• CLAUDE_CODE_EFFORT_LEVEL env var being set and read by a spawned claude subprocess
• output_config.effort frontmatter key surviving the AGENTS.md template substitution
• model_reasoning_effort field surviving serialization into a Codex API request body
• Fast-mode speed: "fast" field reaching an api-runtime request when fast_mode_supported: true

These require spawning real subagents (or stubs thereof) and asserting on the process environment / request payload — a scope that belongs in a future E2E suite under *.slow.test.cjs or dedicated fixture-driven integration work.